Some open-source health related apps for Android I really like.

• Loop Habit Tracker: https://github.com/iSoron/uhabits

  • It's a simple app for reminding you about stuff you should or shouldn't be doing.

• Plees Tracker: https://github.com/vmiklos/plees-tracker

  • Again a very simple app, for keeping track of how much you sleep.

• Paseo: https://gitlab.com/pardomi/paseo

  • App for counting approximately how many steps you've walked. Minimal and seems to be privacy oriented.